REGIONAL PATTERNS OF LACUSTRINE ORGANIC MATTER DEPOSITION IN EASTERN NEW ENGLAND FROM THE LATE PLEISTOCENE TO PRESENT

Lacustrine sediments preserve high-resolution records of climate variability, and a regional context can be gained by incorporating multiples sites. Since lacustrine productivity is largely forced by climatic conditions, we expect to observe coherent patterns in New England lake organic matter preservation since deglaciation.

We present and compare records of sedimentary organic matter from 5 lakes in eastern New England: Pettaquamscutt River Estuary, RI; Sluice Pond, northeastern MA; Pineo Pond, Downeast ME; Tea Pond, western ME mountains, and Conroy Lake, southeastern Aroostook County, ME. Dated sediment cores were analyzed to quantify organic matter (LOI and elemental organic carbon analysis) from the late Pleistocene through the Holocene. Further, elemental ratios (OC/N; OC/S) and stable isotopic values (δ¹³C, δ¹⁵N, δ³⁴S) provide constraints on the provenance of organic matter, paleoproductivity, and paleolimnologic conditions.

Basal ages correspond with previously published deglacial ages, becoming progressively younger from southern to northern sites. Coherency is observed with low organic matter in ME and northeast MA during the Younger Dryas stadial. The RI site lacks a pronounced decrease during the Younger Dryas, suggesting that the effects of this climate interval were more pronounced in northern New England. The records display variability throughout the Holocene, much of which is coherent between sites: 1) Between ca. 11,500 and 10,000 cal BP organic productivity increased, especially in MA and ME, likely resulting from early Holocene warming; 2) Between ca. 9,500 and 9,000 cal BP decreases in organic matter and other proxies suggest lake lowstands; 3) These early Holocene lowstands appear to have lasted longer in coastal MA and coastal ME, as compared to inland sites, and end at ca. 8,000 cal BP; 4) Between ca. 2,500 and 2,000 cal BP low organic matter preservation is observed in most lakes; and 5) Between ca. 1,000 and 500 cal BP organic matter increases, perhaps related to the Medieval Warm Period. The analysis of multiple lakes enables the interpretation of regionally coherent climate variability in New England, however local climate and/or environmental conditions overprint the regional climate signal in individual records.